The radiotherapy using a radiotherapy device, is to make the patient's targets rotatively irradiated as per the work principle of rotation focusing, with the target tissues at the rotary focus subjected to the maximum dose of radiation while the healthy tissues to an instantaneous tolerable dose of radiation, so as to kill the targets while sparing the surrounding healthy tissues. As a result, the aim of radiotherapy can be achieved. A radiotherapy device is disclosed in the patent of multi-source whole-body radiotherapy device with Chinese Patent Publication Number CN 1275410. The radiotherapy device includes a source carrier, a rotary ring fixed to the source carrier, a collimator carrier, a rotary ring fixed to the collimator carrier, a rotary support, and a fixed rotary support ring. Multiple rolling bearings are positioned between the rotary support ring and the rotary ring of the source carrier, as well as between the rotary ring of the source carrier and that of the collimator carrier respectively, forming a rotary fit with axial localization. The source carrier and the collimator carrier can rotate around the same rotary axis respectively, and multiple radiation sources distributed in the source carrier irradiate on a shared focus at the rotary axis through radiation channel in the source carrier and the collimator carrier. The collimator carrier is equipped with collimators, divided into groups as per different apertures. The collimators of each group are distributed in the same way as the radiation sources in the source carrier. The radiation sources and the radiation channel in the source carrier are distributed radially in a sectorial area with angle of less than 90 degrees, and axially in a sectorial area with angle of less than 60 degrees. The interior rotary radius of the collimator carrier is 56 cm, smaller than the human body width. The diameter of the collimator carrier rotary ring is 1 m.
The rotary support of the above-mentioned device is equipped inside with the rotary support ring, the rotary ring of the source carrier and of the collimator carrier. Its shortcomings are that the three inlaid slip-on rotary rings reduce the treatment space and the rotary scope of the collimator carrier, and increase manufacturing difficulty and cost; and with the source carrier and the collimator carrier connected at both ends with the rotary support through the rotary ring, whose minimum diameter is 1 m, the bigger rotary ring of the source carrier and of the collimator carrier as well as complicated manufacturing process, affect the coaxial rotation accuracy of the source carrier and of the collimator carrier during rotary focusing of the radiation beam, thus affecting the focusing accuracy of the radiation beam from the sources and lowering the radiotherapy effect.